GB2196422A - Simulated solid fuel gas fire - Google Patents

Abstract

A simulated solid-fuel burning heating appliance comprises a mass of particulate refractory material 18a in an open-topped tray 15, the base of the tray having one or more openings 17, and a gas supply pipe 1, 4 in a sealed arrangement with the base of the tray, the gas supply being so arranged that, in use, a fuel gas/air mixture passes along the pipe then through one or more of the openings 17 and out through the mass of refractory material. Such a gas fire provides an optimum fuel gas/air mixture throughout the lifetime of the appliance but still provides an aesthestically pleasing simulation of a solid fuel fire. <IMAGE>

Description

SPECIFICATION Gas fire This invention relates to heating appliances which burn gaseous fuel, but more particularly to heating appliances in which a gaseous fuel passes through a particulate refractory material simulating, the combustion of fuel in a solidfuel fire.

Such simulated solid-fuel fires are known, see for example U.K. Patent No. 1 541 423 (D. A. Mitchell), in which the fire comprises a mass of particulate refractory material in an open-topped tray, a plurality of refractory bodies shaped and coloured to simulate solid fuel mounted on top of the mass of particulate material, a perforated tube embedded in the mass of particulate material with an end of the tube extending out of the mass of material, such that gaseous fuel supplied to the tube flows out of the perforations and through the mass of particulate material to spaces between the refractory bodies and a pipe defining an air passage for providing extra combustion air to the gaseous fuel flowing to only some of the spaces between the bodies so that, in use, the gaseous fuel provided with the extra combustion air burns with a nonluminous flame and that without the extra combustion air burns with a luminous flame thereby simulating a solid fuel fire. The Mitchell fire preferably incorporates means which allow the user to adjust the rate of flow of the extra combustion air.

Although such a fire may be aesthetically very pleasing to the eye it does, in fact, suffer from at ieast two disadvantages.

Firstly, it is desirable that a heating appliance adapted to burn a gaseous fuel allows the fuel to burn with the optimum fuel/air mixture. The Mitchell fire burns its fuel with two mixtures, one of relatively high extra air and one of relatively low extra air proportions respectively and cannot therefore operate at the optimum efficiency level.

Secondly it is desirable that the optimum fuel/air mixture is maintained throughout the lifetime of the appliance. The Mitchell fire can only permit part of the fuel supply to burn at the optimum mixture and, as the user can vary the mixture in any case, it is extremely unlikely that an optimum mixture would be maintained.

On the other hand it is desirable to provide an effective simulation of a solid fuel fire.

According to the present invention a simulated solid-fuel burning heating appiiance comprises a mass of refractory material in an open-topped tray, the base of the tray having one or more openings, and a gas supply pipe in a sealed arrangement with- the base of the tray, the gas supply being so arranged that, in use, a fuel gas/air mixture passes along the pipe then through one or more of the openings and out through the mass of refractory material.

Preferably there is a diffuser co-operating with an opening in the base of the tray, and adapted to spread the gas/air mixture over a relatively large area of the base of the tray.

The diffuser may comprise a plate covering, but a short distance above an opening in the base of the tray, the plate extending over a relatively large area of the base of the tray, so that the gas/air mixture is diverted by the plate to the periphery of the plate before being allowed to percolate upwardly through the mass of refractory material. This arrangement provides outlet slits all round the plate, between the underside of the plate and the topside of the base of the tray.

In a preferred construction the opening in the base of the tray is of relatively large rectangular shape and the cover plate covers this opening and extends over a marginal part of the base all round the opening.

The gas/air supply pipe may be sealed directly to a rectangular plenum chamber and the plenum chamber may be sealed to both the gas/air supply pipe and the underside of the tray which surrounds an opening such that, in use, the fuel gas/air mixture may pass from the gas/air supply pipe, into the plenum chamber and then distributed through substantially all of the slits around the cover plate.

The invention will now be described by way of example only with reference to the accom panying drawings in which: Figure 1 shows a cross sectional side elevation of a gas fire; Figure 2 shows a rear elevation of the gas fire looking in the direction of arrow II in Figure 1; and Figure 3 shows an underneath plan of the gas fire looking in the direction of arrow Ill in Figure 1.

A gas-fired simulated solid-fuel fire has an open topped tray 15 which in use is located in a domestic fire at the level of the conventional firegrate; the tray being filled with particulate refractory material 18a. A set of solid refractory bodies 1 8b each simulating a piece of solid fuel (e.g. coal or logs) is formed into a stack resting on the particulate material.

Provision is made for supplying gaseous fuel upwardly through the particulate material, so that when the fuel is ignited it gives off heat mainly by convection, but also it impinges on the refractory bodies 1 8b and causes parts of them to irradiate, thereby simulating burning pieces of solid fuel.

A metal fuel pipe 1 is sealed at its input end 2 to a pipe coupling means 3, and at its other end 4 to a rectangular plenum chamber 5.

The pipe coupling means 3 comprises a gas entry fitting 6 attached to the pipe 1 by means of one or more bolts 7, there being a plug 8 fitted into the fitting 6 having a rela tively small central bore 9 or a multiple hole gas injector. The gas entry fitting 6 incorporates means (not shown) which allows a standard gas supply pipe (not shown) to be readily connected and sealed to it.

In use fuel gas 10 slowly enters through the restricted entry provided by the gas entry fitting 6 and in passing through the narrow bore 9 in the plug 8 its speed is much increased.

The high speed fuel gas indicated at 10a moves along the pipe 1 but, shortly beyond the end of the bore 9, it passes one or more air entry holes 11 in the pipe 1. The pressure differential between the gas 1 0a leaving the bore 9 and the air outside the pipe is such that air 12 is sucked into the pipe through the air holes 11 to mingle with the gas. The proportion of fuel gas to air will depend largely upon the pressure differential between the interior and the exterior of the pipe and the relative sizes and spacings of the air holes 11.

Once the optimum fuel gas to air ratio has been determined for the particular fuel gas to be used, the spacing and sizes of the air holes can be very easily determined by trial.

The fuel pipe 1 is sealed at its other end 4 to the rectangular plenum chamber 5 and, as is clear from Figure 2, a semi-circular cross section extension of the pipe extends across the width of the chamber but opens on the inside into the chamber.

The open topped plenum chamber 5 registers with a rectangular hole in the base of the tray 15, and has a flange 13 which is securedand sealed to the underside 14 of the metal tray 15 by means of rivets 16. In use therefore the fuel gas/air mixture fills the plenum chamber 5 and rises into the tray passing through the opening 1 7 in the base of the tray 15.

However, as will be appreciated from Figure 1, one function of the tray 15 is to retain the powder 18a which, in the absence of a closing member- -of the opening 17 could fall into the plenum chamber 5 and or into the fuel pipe 1 thereby possibly causing a dangerous blockage of the fuel path. As the simulated solid-fuel elements 18b could vary greatly in size, possibly from large sandlike grains to blocks having dimensions of several centimeters, it is clear that a closing member must define apertures having reasonable dimensions.

In the present case a metal plate 19, which overlaps all the edges of the opening 17 in the tray 15, is fixed to the tray by means of the same rivets 16 used to seal the tray 15 to the plenum chamber 5. The plate 19 closes the opening 17, but is spaced-from the base of the tray 15 by a plurality of washers 20 each one of which surrounds the stem of each rivet 16 between the metal plate and the tray such that a plurality of narrow slits 21 are defined between the said tray and the said closing member, all round the periphery of the plate 19.

As will be appreciated, once more from Figure 1, another function of the tray/cover plate arrangement is to diffuse the fuel gas/air mixture over a wide area of the particulate matter 18a to give as good a spread of the 'fire' effect as possible. This is an important aspect of the present invention as there is only one ratio of fuel gas to air that is available, i.e. the optimum, so it isall the more important for the slits to provide a fuel gas/air distribution the flames from which provide a realistic solid-fuel effect fire.

Claims (6)

1. A simulated solid-fuel burning heating appliance comprising a mass of refractory material in an open-topped tray, the base of the tray having one or more openings, and a gas supply pipe in a sealed arrangement with the base of the tray, the gas supply being so arranged that, in use, a fuel gas/air mixture passes along the pipe then through one or more of the openings and out through the mass of refractory material.

2. A simulated solid-fuel burning heating appliance according to Claim 1 wherein there is a diffuser cooperating with an opening in the base of the tray, and adapted to spread the gas/air mixture over a relatively large area of the base of the tray.

3. A simulated solid-fuel burning heating appliance according to Claim 2 wherein the diffuser comprises a plate covering, but a short distance above an opening in the base of the tray, the plate extending over a relatively large area of the base of the tray, so that the gas/air mixture is diverted by the plate to the periphery of the plate before being allowed to percolate upwardly through the mass of refractory material.

4. A simulated solid-fuel burning heating appliance according to Claim 3 wherein the opening in the base of the tray is of relatively large rectangular shape and the cover plate covers this opening and extends over a marginal part of the base all round the opening.

5. A simulated solid-fuel burning heating appliance according to any preceding claim or claims wherein the gas/air supply pipe is sealed directly to a rectangular plenum chamber and the plenum chamber is sealed to both the gas/air supply pipe and the underside of the tray which surrounds an opening such that, in use, the fuel gas/air mixture may pass from the gas/air supply pipe, into the plenum chamber and then distributed through substantially all of the slits around the cover plate.

6. A simulated solid-fuel burning heating appliance as hereinbefore described with reference to the accompanying drawings.